1. Field of the Invention
The subject matter disclosed herein relates to coolant pump and radiator fan drive for use with a reciprocating liquid-cooled internal combustion engine.
2. Related Art
Liquid-cooled reciprocating internal combustion engines typically employ a coolant pump (commonly termed a “water pump”), to circulate coolant between a heat exchanger, commonly termed a “radiator,” and the engine. The radiator is an air-to-liquid heat exchanger which usually has a fan to pull ambient air through the radiator core. On heavy duty vehicles, the fan is usually powered by the engine's crankshaft. With most engines, the fan and a pump impeller are mounted on a single shaft extending through the coolant pump to a fan clutch. Unfortunately, with this arrangement it is not possible to drive the fan at a speed which is different from the water pump speed except by the use of a fan clutch, which is allowed to slip, so as to drive the fan at a slower speed than the water pump during certain operating conditions. Under some conditions, it is not desirable to drive the fan and water pump or coolant pump at the same speed; with some engines, it may be desirable to drive the fan at a slower speed or at a greater speed than the coolant pump.
It would be desirable to provide a dual drive for a liquid coolant pump and radiator fan, permitting the fan and coolant pump to be driven independently, so as to permit optimal tuning of the pump and fan drive speeds.